The present invention relates to a projection television receiver, and more particularly to a cathode-ray tube and an optical structure around lenses in a projection television receiver for magnifying and projecting an image displayed on a face surface of the cathode-ray tube by using a projection lens.
In the projection television receiver, recently, it is a mainstream technology to inject a clear refrigerant liquid into an optical coupling of a cathode-ray tube and a projection lens for the purpose of enhancing the contrast performance and cooling.
The optical coupling includes a container (called also radiator hereinafter) and a refrigerant liquid contained in the container. The container is generally made of aluminum die-cast, and the aluminum die-cast is treated on the surface, and a black alumite film is formed.
A conventional projection television receiver is explained by referring to the drawing. FIG. 3 is a sectional view showing an example of the optical coupling in the conventional projection television receiver.
In FIG. 3, a cathode-ray tube 1 is sealed and fixed to a radiator 4 through a first O-ring 5. A projection lens 2 is sealed and fixed to the radiator 4 through a second O-ring 6. The region enclosed by the cathode-ray tube 1, projection lens 2 and radiator 4 is filled with a refrigerant liquid 3.
The radiator 4 is made of aluminum die-cast, and an alumite film 7 is formed on the surface. The alumite film is an aluminum oxide film formed by anodic oxidation of aluminum die-cast.
The conventional forming process of alumite film, however, required acid treatment as pretreatment for removing impurities on the die-cast surface. This acid treatment caused to roughen the surface of the radiator 4. If control of this treatment process is insufficient, the surface roughness of the radiator 4 fluctuates largely, possibly leading to seal failure. This seal failure involves a problem in quality control because it may lead to a liquid leak accident.
Further, to satisfy the optical performance, the surface of the radiator 4 is dyed in black. This black dyestuff is sometimes peeled off from the surface of the radiator 4 to drop into the refrigerant liquid. To prevent such peeling, it requires a step of cleaning the radiator 4 before assembling, and the step of cleaning the radiator 4 has caused to increase the number of manufacturing steps.
The projection television receiver of the invention comprises a cathode-ray tube having a face surface, a projection lens disposed ahead of the face surface, a container disposed between the face surface and projection lens, and liquid filling up the container, in which the container has a fluoride resin film disposed at least inside of the container, and the fluoride resin film contacts with the liquid.
Preferably, the projection television receiver further comprises a first sealing member disposed between the container and face surface, and a second sealing member disposed between the container and projection lens, in which the first sealing member is disposed in a state tightly contacting with the face surface and fluorine resin film to prevent the liquid from leaking out from between the container and face surface, and the second sealing member is disposed in a state tightly contacting with the projection lens and fluorine resin film to prevent the liquid from leaking out from between the container and projection lens.
Preferably, the fluoride resin film has a stable corrosion resistance to the liquid.
In this constitution, liquid lead is prevented. Further, peeling of film is prevented. A projection television receiver of high reliability is obtained. Moreover, the assembling process is curtailed, and the manufacturing cost is reduced.